Large granular lymphocytosis terminating in a polymorphous B-lymphocytic proliferation after low-dose cyclophosphamide therapy: a case report with necropsy findings.

A 70-year-old man presented with clonal large granular lymphocytosis of T-suppressor/cytotoxic immunophenotype, neutropenia, paraproteinemia, and proneness to infection. The patient became severely leukopenic during 14 days of chemotherapy with low-dose cyclophosphamide, and remained so after discontinuation of the drug. Clinically, he was thought to have prolonged chemotherapy-induced marrow hypoplasia. At death, 16 days after the last dose of chemotherapy, autopsy confirmed bone marrow hypoplasia and revealed that well-differentiated, polymorphous, and (immunophenotypically and genotypically) polyclonal B-lymphocytes predominated in normal hematopoietic and lymphoid organs. A similar lymphoid infiltrate was intimately associated with multiple ulcers and smooth muscle necrosis in the stomach. These terminal findings resemble B-lymphoproliferative conditions described in certain forms of immune deficiency.